1. Field of the Invention
This invention relates to an air cleaning and circulating apparatus of the hassock fan type which contains negative ion generators and a charged filter to treat and circulate air.
2. Description of the Prior Art
There are a multitude of devices available that are used to clean and circulate air. One such device uses a high voltage negative ion generator in combination with a positively charged collector plate, the ion generator producing a fountain of ions around the device. As there is no air behind the ions they are not evenly distributed throughout the room and being negatively charged are attracted to walls, rugs and curtains, which are positively charged and therefore cause these areas to become dirty at a rate faster than normal. In addition, the collector plate is inefficient as it does not remove a large portion of the charged particles.
The use of fans of the hassock type to circulate air is well known, such fans are very efficient in high volume air circulation due to their 360.degree. radial air flow at high volume levels which can be in the range of 400 to 600 CFM.
Due to this high volume air movement in hassock fans, filters of the mechanical type in combination with a hassock fan, which would filter 90% of the particles from the air are impractical. The impracticality results from the restriction in discharge air flow that is necessary to provide high efficiency, which restrictions would result in a typical air flow drop from 400 CFM to 100 CFM. This air flow problem would also be apparent in other fan filter configurations due to the flow restrictions necessary to achieve a high level of filtering efficiency.
The U.S. Pat. No. 2,431,724, to Adyt shows a vertical axis fan which has an ozone unit in its base, and which provides for air circulation but does not contain filtering media.
The U.S. Pat. No. 3,747,300, to Knudson shows a portable electrostatic air cleaner with three filter elements, which are a mechanical filter, an electrostatic filter, and an activated charcoal filter, and which also suffers from the problems described above.
The U.S. Pat. No. 3,716,966, to De Seversky illustrates a vertical axis hassock type fan, which is surrounded with a wet electrostatic precipitator, and which provides a complicated structure that requires frequent maintenance, and does not provide the desired high air flow.
The U.S. Pat. No. 3,783,588, to Hudis illustrates the use of an electrostatically charged air filter for air filtration, the filter being provided with openings for air flow and which may be mounted in combination with an axial type fan. The Hudis structure is fragile, complicated and does not provide a high rate of air flow.
The structure of my invention provides for efficient air filtration at a high air flow rate and provides a well distributed stream of negative ions.